Self-assembled monolayer (SAM) is a monolayer coated on a specific surface at a molecular level, and the self-assembled coating layer consists of a head group capable of spontaneously forming a strong bonding with a target surface and a head group capable of introducing desired chemical/physical properties onto the coated surface. For recent three decades, many efforts have been made to develop self-assembled coating layers having various functionalities, because self-assembled coating layers have an advantage of easily providing the surface with functionality and thus can be economically applied to various fields. Typically, corrosion of metals can be effectively prevented by coating the metals with the self-assembled coating layer to block direct exposure to external environment. In addition, the self-assembled coating layer controls the coefficient of friction of the surface and thus applied to various fields such as reduction in metal abrasion resistance, introduction of a chemical functional group for detecting a biomolecule, hydrophilicity of the surface, introduction of an antifouling property to the surface, and the like.
However, once contaminated, the self-assembled coating layer may also cause a reduction in the provided functionality or corrosion of surface under the coating. Therefore, studies on the self-assembled coating layer are faced with the challenge of recovering the contaminated surface or maintaining the surface uncontaminated. Many methods have been attempted to remove the contaminated self-assembled coating layer, but they have problems. Most of the methods damaged the surface or did not give satisfactory removal results, upon removing the contaminated self-assembled coating layer. Recently, a self-assembled coating layer to be easily removed has been successfully synthesized. However, the method is very complicated, and has a very low efficiency or a limitation in its application.